Applied Research And Implementation Of LDAP-Based Mail System And A Proposal For Relevant Protocol Extensions In Mail System

Email Service is one of the primitive services of the Internet, and the most important one as well. With the rapid development of Internet within these years, the number of people using Email is booming, which brings lots of new problems to the system administrator in managing the Email system. For example, a lot of disadvantages are found in the traditional MX-based or Mailtable Mail Relaying Mechanism. While the management of this information service is very important for the application of Enterprise Network or Campus Network. Therefore, adopting Directory Service to solve the problems of traditional E-mail system and extending SMTP to support LDAP in the aspect of the protocol have become one of the research tasks in the application of Internet in recent years.This paper firstly sets about the relevant protocols which are used in the Mail System and Directory Service, and then explores and analyses the operational principle of Mail System, POP, IMAP and Directory Service. After that, it induces the occasions that LDAP can be applied and the environment that LDAP can supports. Finally, it concludes the aspects which need to be improved in the existing Mail System.Relaying based on the traditional MX and Mailtable shows many disadvantages in practice. This paper discusses the LDAP-based mail relaying mechanism and its advantages in detail, and carries out a relevantly experimental system in Unix or Linux Platform using C. Some testing works have been done so as to compare this experimental system with the traditional MX-based relaying mechanism.The extension of authentication function for SMTP can be found in RFC2554.This extension to SMTP provides a standard interface for authenticating. In this paper we bring forward a LDAP-based authentication mechanism to control email sending and it has been implemented in Shantou University. This method isproved effective in preventing unauthorized people from sending spam mails, such as mails concerning the sayings endangering the nation, viruses and using others' email address to send mail.With the development of Internet and the appearance of new application, the function of Mail System must be extended continuously in order to meet new needs. This paper discusses the extension of the protocols pertinent to Mail System, and brings forward some advice.